Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 11

# A Closed Cylindrical Tube Containing Some Water (Not Filling the Entire Tube) Lies in a Horizontal Plane. - Physics

MCQ
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A closed cylindrical tube containing some water (not filling the entire tube) lies in a horizontal plane. If the tube is rotated about a perpendicular bisector, the moment of inertia of water about the axis __________ .

#### Options

• increases

• decreases

• remains constant

• increases if the rotation is clockwise and decreases if it is anticlockwise

#### Solution

increases

Moment of inertia of a mass is directly proportional to the square of the distance of mass from the axis of rotation.
Therefore, we have

$I \propto r^2$

As the tube is rotated, water is collected at the end of tube because of centrifugal force and distance from the rotation axis increases. Hence, moment of inertia increases.

Concept: Values of Moments of Inertia for Simple Geometrical Objects (No Derivation)
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#### APPEARS IN

HC Verma Class 11, 12 Concepts of Physics 1
Chapter 10 Rotational Mechanics
MCQ | Q 13 | Page 193